Ask someone to name the most unhittable pitch in baseball and you're likely to get a variety of answers. Of course, unhittable is usually figurative. Even the nastiest offerings yield hits from time to time.

But so far this season, one pitcher has a pitch that is staking a literal claim to the title of most unhittable:

Lowest BA allowed on individual pitch type, 2022
Minimum 30 plate appearances ending on that pitch type
Patrick Sandoval’s changeup -- .000
Nabil Crismatt’s changeup -- .057
Corbin Burnes’ curveball -- .067
Amir Garrett's slider -- .069
Tony Gonsolin’s slider -- .071
Aaron Loup’s sinker -- .071
Matt Foster’s four-seam fastball -- .071

Hitters have gone 0-for-30 against Sandoval’s changeup. In 35 plate appearances ending on the pitch, the Angels left-hander has recorded a whopping 20 strikeouts, which equates to a 57.1% strikeout rate -- a nearly unparalleled mark among starting pitchers on any individual pitch type.

Highest strikeout rate on individual pitch type, SP, 2022
Minimum 25 plate appearances ending on that pitch type
Shohei Ohtani’s splitter -- 61.5%
Patrick Sandoval’s changeup -- 57.1%
Eric Lauer’s four-seam fastball -- 56.1%
Shane McClanahan’s curveball -- 51.9%
Germán Márquez's knuckle-curve -- 51.9%

More than half the time this season, when batters have swung at Sandoval’s changeup, they’ve missed. His 52.4% whiff rate on changeups is the seventh highest any hurler has registered on a single pitch type this season (min. 50 swings).

Sandoval's changeup, which he throws almost exclusively to right-handed batters, is driving a breakout that began last season, but it wasn't always his go-to pitch.

"I never thought it was like my best pitch. I always thought it was my curveball," Sandoval told MLB.com's Rhett Bollinger on Friday. "Growing up just seeing the big looper. But when I got to pro ball, it was changeup that was better than anything else."

Selected by the Astros in the 11th round of the 2015 Draft out of Mission Viejo High School, which is a short drive from Angel Stadium, Sandoval was traded to the Halos for catcher Martín Maldonado in 2018. According to Sandoval, he started throwing his changeup more once he got to the Angels.

"Yeah, I think my first outing [in the Angels organization], they kept swinging and missing at the changeup, so we just kept calling changeups and I just kept throwing changeups," he said.

Sandoval made his MLB debut in 2019, but after posting a 5.33 ERA across 2019-20, he didn’t make the Angels’ Opening Day roster last season, and his first start of 2021 didn’t come until May 17. However, he recorded a 3.31 ERA and a 27.8% strikeout rate in his final 12 starts before a stress reaction in his back ended his season in August.

Healthy again, the 25-year-old has taken another step forward in 2022. He’ll enter his scheduled start Sunday against the A’s with a 2.03 ERA and 27 strikeouts over 26 2/3 innings. He has surrendered just three extra-base hits, none of them home runs, while facing 112 batters.

What’s surprising is that Sandoval is doing so well despite throwing a four-seam fastball that has been anything but unhittable. While his changeup has allowed the lowest average of any pitch type in MLB (min. 30 PAs ending on that pitch type), his four-seamer has yielded the highest, with opponents going 14-for-27 (.519) against it.

His changeup was a big part of his success last year as well, but he’s taken it to another level in 2022, with improvement in two key areas:

More movement

A year ago, Sandoval added 1.7 inches to his average horizontal changeup movement, going from 11.4 inches of arm-side run in 2020 to 13.1.

In 2022, he’s added another 2.4 inches, increasing his horizontal movement to 15.5 inches, which means that the changeup Sandoval is throwing this season has 4.1 more inches of arm-side run -- running down and away from right-handed batters -- on average than his changeup from two years ago.

To put it another way, his changeup has gone from a pitch that had 1.6 inches less horizontal movement than other MLB changeups with similar velocity to one that has 1.5 inches more.

He's added 1.6 inches of drop, too, increasing his vertical movement from 28.2 inches to 29.8 inches since 2021.

Sandoval has a simple explanation for how he gets his changeup to move like it does, relying on arm action, grip and gravity.

"The key is throwing the crap out of it and letting the [circle-change] grip work," he said. "Let gravity take hold."

Sandoval also throws a slider that gets 7.4 inches of glove-side break (moving down and in on right-handed batters), or 2.2 inches above average. Opponents are hitting .143 (4-for-28) with six K’s against his slider this season, and the pitch’s spin profile and velocity make it the perfect complement to his changeup.

The spin axis of his slider is almost 180 degrees from that of his changeup, a phenomenon known as spin mirroring that can make it even tougher for batters to discern what pitch is coming before one pitch breaks toward the glove side and the other runs toward the arm side. Both pitches sit around 85 mph -- 84.5 mph for his changeup and 85.5 mph for his slider.

Over the past two seasons, the combo has been vital for Sandoval.

Opponents vs. Sandoval, 2021-22
On changeups/sliders: .137 BA (32-for-237), 104 K's
On four-seamers/sinkers/curveballs: .326 BA (59-for-181), 17 K's

Better location

It's not that Sandoval's changeup location was poor last season, but this year he's been so sharp that hitters don't have a chance.

Sandoval has thrown 49.2% of his changeups in the shadow zone, the area one baseball's width inside and one baseball's width outside the borders of the strike zone. Last season, it was 40%. 

Meanwhile, the percentage of changeups he's thrown in the heart of the plate has dramatically dropped, from 17.3% to 10.4%.

These heatmaps comparing Sandoval’s location on in-zone changeups in 2021 and 2022 illustrate the improvements he’s made. Though his strategy hasn’t changed in terms of targeting the bottom of the zone and the arm-side corner of the plate, he’s doing a better job of locating in both of these areas and avoiding elevated pitches that hitters can attack.

Given all of the other intriguing storylines surrounding the Halos, it's possible you haven't even noticed Sandoval. But considering how much the Angels have perennially struggled to put together a dependable rotation, the lefty's continued development could prove most crucial as the club looks to reach the postseason for the first time since 2014.

It's going to be tough to do better than he has so far, especially with his changeup, but he's not yet satisfied.

"I've had one good outing, and the rest have just been, I think managing damage has been a good way to assess the other four," he said. "I feel like I'm keeping our team in games. And that's the job of a starting pitcher. So you know, I think as the year goes on, I'll get more consistent, especially because I'm still kind of fighting the changeup a little bit.

"Once that gets going, it'll be fun."